Telephone-exchange system



April 22, 1924. 1,491,348

' L. KELLER ET AL TELEPHONE EXCHANGE SYS TE'M Filed AuK. 30, 1920 Closes on 6 lasf sfe/o fnvenfor: Leo Keller: Char/es L. Good/um. y a Affy.

TES

rArEnr LEO KELLER AND CHARLES L. GOOBRUM, OF NEW YORK, N. Y., ASSIGNOR-S TO WEST- ER'N ELECTRIC OOIVIPANY, INCORPORATED, OF NEVI YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONEEXCHAI\TGE SYSTEM.

Application filed August 30,1920. Serial No.406ff73i To all 11: 71.0121- it may concern Be it known that we, LEO lineman and Crn-xnmisli. fioonnuiu, citizen ot the United States, residing at New York, in the county of New York and State of New York, have invented certain new and usetullmprovements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and particularly to machine switching systems coniiprisinpj private branch exchange working.

The object ot the invention is the provision of means for discriminating between calls directed to different points whereby, on

certain calls, an operator will be called in to helpcstablish the connection.

With large cities where ma-nypeople live in apartment houses it has been found economical to provide an Operator to care for a block of apartment houses. It also happens that within these blocks there are individual lines, the service to which must not be supervised by an operator. *l-lencethe means of the present invention have been devised to care for this mixed service in the most economical and approved n'ia-nner. There is pro vided a trunk line from the central exchange having a branch to an operators position. On calls to an apartment house, an indicator switch is set to apprise the operator of the particular apartment house called, after which she may inquire the particular apartment Wanted and complete the connection. On calls to an individual line, an:indicator switch is set as usual but the setting in accordance with the number of an individual line causes it to be automatically restored, and the operator is notcalled in and the ca ll proceeds without hindra ncc.

The invention is diagrammatically illustrated in the accompanying drawing. Where a. preferred means of accomplishing the desired results is shown.

heir a subscribcr.sa v substation l, "r'QfiiOYt-S his receiver from its hook, a line finder 3 establishes a connection between the calling line and a selective switch t. Let it beassumed that the call isr't'or a subscriher at a certain apartment house. The subscriber at sub-station 1 will thereupon set the switch 4-. whichinay be of any wellknown construction onto the terminals of the l pou the line circuit leading in the direction of the wanted number-whose terminals are 5, 6 and l. 'A circuit will now be established for relay 8 which may be traced from battery,

through the left-hand winding of relay 8, the

upper limb of the trunk line, through the loop of the calling subscribers line, the

lowerliinb of the subscribers line andtrunk, the right-hand winding of relay 8, to ground.

Relay 8 is energized in this circuit, and through the movement of its left-hand armature-closes a circuit for relay 9. Relays 8 and 9 cooperating close a circuit between the sec ondary coils 10 and 11 of the repeating c-oil'23 from winding 10, through the righthand armature and front contact of: rela 8, the

right-hand armature and trout contact of relay 9, contact 12, ternnnal 13 to the coil 11.

A circuit is now established from ground, the inner right-hand armature and front contact of relay 9, the lett hand armature and normal contact of relay 15, winding of relay 16, to battery and ground. Relay 16 attracts its armature andestablishes a circuit from ground, the armature and trout Contact or relay l6, armature and back con-- tact of relay 17, the oft-normal contact 18 and its lower contact, to the windings oitrelays 19 and 20in parallel, and thence to battery and ground. Relay 19, by attracting its outer lett-hand armature, efitends a: ground through the contact,armature and winding of magnet 21 to battery and ground.

Magnet 21 is a stepping magnet and being self-interrupting causcsthe brushes o't the switch '22 to rotate until the terminals in- -dividual to the 1 link circuit have been found. This is done in thectollowing manuer:

step, brush 2%.- is brought into engagement with terminal 25, whereupon a circuit is established from ground. the armature and back contact of a relay corresponding to relay 16 oi an equivalent link circuit,.terminal 25. brush 24. "front contact and inner-left-hand armatureof relay, 19. winding of relay 191tobattery and ground. In this manner relay 19 is held energized. until the brush 2% comes into engagement with the terminal individital of the link circuit this circuit proceeding .unagnet 86 is energized in to the link: circuit 23. This particular ter minal 25 will be ungrounded due to the energization of relay l6. Thereupon relay 19 will become deenergized, since its orginal circuit was opened by the off-manual contact 18 upon the first step of the brushes of switch 22.

It should be noted at this point that brush 26 makes contact with terminals similar to 13, at which time it lifts these terminals 13 from their contacts 12, in this manner inserting the dial sender 27 in the circuit of the secondary coils of the repeating coil of link circuit 23.

lVhen the brushes of switch 22 come to rest upon the terminals individual to the link circuit 23, relays 19 and 20 become deenergized. Relay 20 thereupon extends the starter wire from oil-normal contact 18, through the left-hand armature and back contact of relay 20 to conductor 28. The circuit is now in a stable, condition awaiting the sending of impulses by the subscriber at substation 1. Let it be assumed that the number of the apartment house called is characterized by the digits 432. The subscriber at substation 1 will manipulate his dial sender 2 to send four impulses. These impulses will be in the form of short interruptions of the line circuit whereby relay 8 will become deenergized four times in quick succession. Upon the first deenergization, a circuit will be closed from the lefthand armature and back contact of relay 8, the left-hand armature and front contact of relay 9, terminal 29, brush 30, back contact and ri 'hthand-armature of rela 1 19 winding of side switch magnet 81, to battery and ground, and in parallel with the winding of side switch magnet 31, through side switch arm 32 and its first position contact, stepping magnet to battery and ground. Stepping magnet 33 will become energized in this circuit and rotate the brush 34 one step. In accordance with the four impulses sent, brush 34 will therefore be set upon terminal 35, the side switch magnet 31 in the meantime remaining energized throughout the series of impulses. At the end of this series of impulses, side switch magnet 31 becomes deenergized and causes the rotation of the side switch arms to their second positions.

The vibration of its armatures by relay 8 also causes the opening of the circuit be tween coils 10 and 11, whereby the selective switch 1.4 is set in accordance with the digit 4, and the trunk to selective switch is selected.

The subscriber at sub-station 1 now sends a second series of impulses corresponding to the digit 3, whereupon the same action as before takes place with this, exceptionthat place of magnet 34 and the wiper 38 is finally set upon the terminal 39 corresponding to the digit 3. it the same time the rotary connector 65 is set in accordance with the digit 3 and the trunk line to switch 43 is selected.

The subscriber at sub-station 1 now sends the last series of impulses corresponding to the digit 2, whereupon magnet 40 is energized and the brush 41 is set upon the terininal 42. Switch 43 selects the trunk to switch 66 which is located in the particular apartment house wanted. At the end of this series of impulses, the sideswitch mag net 31 becomes deenergized and moves the side switch arms into their fourth positions, whereupon a circuit is established from battery, the fourth position contact, and the side switch arm 44, and thence in parallel through signal lamps 45, 46 and 47 to brushes 41., and respectively, and thence through the back contact and righthand armature of side switch magnet 31 to ground. The three signal lamps 45, 46 and 4'? indicate to the operator that a. subscriber has called for a party located in the particular apartment house characterized by the digits 432. She may thereupon manipulate the listening key 48 and communicate with the subscriber at sub-station 1, inquiring the particular subscriber wanted at the apartment house called and having received this information, may manipulate the dial sender 27 to set the selective switch 66 upon the terminal of the called sub-station 50. hen her duties have been performed, she depresses the key 51 which places ground on the winding of release magnet 52. Release magnet 52 thereupon locks up to ground through th off-normal contact 53, and at the same time causes the energization of relay 15, through its outer righthand armature. Relay 15 looks up through its right-hand armature to the ground of the inner right-hand armature of relay 9, thereby releasing relay 16. The rel-ease magnet causes the brushes of switch 22 to return to their normal position. Thereupon a cir- ,cuit is closed. from ground, the off-normal contact 54 to conductor 55, which will be extended through the off-normal contact 56 of the switch represented by brush 41, the back contact and armature of magnet 40, the windin of magnet 4.0, to battery and ground. Magnet i0 will interrupt its own circuitand set the brush 41 to its normal position. In the same manner brushes 34 and 38 will be returned to their normal positions. Re lease magnet 52 also returns side switch wipers 32 and 34 to their normal positions by mechanical connections.

The conversation may now proceed with the circuit in this condition. Relays 8, 9 and 15 are energized and the circuit between coils 10 and 11 is closed through the righthand armatures of relays 8 and 9. Upon the close of the conrersation on the deenergiza tion of relays S and 9, ground will be placed on the terminal 7, which will cause the return to normal of: the switches 3 and 4, and the opening of the circuit between the coils 10 and 11 will cause the return to normal of the other switches 14, 65, 43 and 66 in this circuit in the usual manner.

Let it be assumed that the call was for an individual station, such as #60. If the sub-station is characterized by hundreds digit 3 or by tens digit 1, when the brushes 34; or 38 come to rest in engagement with their third or first terminals, respectively, a circuit will be closed upon the deenergization of the side switch magnet 81, from ground, the right-hand armature of side switch magnet 31, brush 3 its third contact or brush 38, its first contact, conductor 61, winding of release magnet 52, to battery and ground. Thereupon the switch 22 will be returned to normal and in due course the switches represented by brushes 34 or 38 will be returned to normal in the usual manner. Thus on a call to an individual subscriber, an indicator represented by the signal lamps such as 45, 46 and 47 will not be operated and the operator will not be called in to help establish the connection.

Release is accomplished in the same manner as heretofore described.

hat is claimed is:

1. In a telephone system, a link circuit, a plurality of individual telephone lines, a plurality of trunk lines, means for extending said link circuit to said lines, an indicator associated with said link circuit, means for setting said indicator in accordance with the line to which said link circuit is extended, and means for restoring said indicator to normal when said link circuit is extended to one of said individual telephone lines.

2. In a telephone system, a link circuit, a plurality of individual telephone lines, a plurality of trunk lines, means for extending said link circuit to said lines, an indicator associated with said link circuit, means for setting said indicator in accordance with the line to which said link circuit is extended and means for rendering said indicator ineffective when said link circuit is extended to one of said individual telephone lines.

3. In a telephone system, a subscriber controlled link circuit, a plurality of individual telephone lines, a plurality of trunk lines, means for extending said link circuit to said lines, an indicator associated with said link circuit, means for setting said indicator in accordance with the line to which said link circuit is extended, and means for restoring said indicator to normal when said link circuit is extended to one of said individual telephone lines.

4. In a telephone system, a link circuit, a plurality of individual telephone lines, a plurality of trunk lines, means for extending said link circuit to said lines, an indicator circuit associated with said link. circuit responsive to the manipulation of said link circuit comprising means for identifying the particular trunk line to which said link circuit is extended, and means for releasing said indicator circuit when said link circuit is extended to one of said individual telephone lines.

5. In a telephone system, a link circuit, a plurality of individual telephone lines, a plurality of trunk lines, means for extending said link circuit to said lines, a visual number indicator associated with said link circuit, means for setting said indicator in accordance with the line to which said link circuit is extended, and means for restoring said indicator to normal position when said link circuit is extended to one of said individual telephone lines.

6. In a telephone system, a link circuit, a plurality of telephone lines of different character, means for extending said link circuit to said lines, an indicator associated with said link circuit, means for setting said indicator in accordance with a plurality of digits designating the line to which said link circuit is extended, and means for restoring said indicator to normal position when said link circuit is extended to a telephone line of a certain character.

7. In a telephone circuit, a link circuit, a plurality of telephone lines of different character, means for extending said link circuit to said lines, an indicator comprising means for visually indicating a plurality of digits associated with said link circuit, means for setting said indicator in accordance with the line to which said link circuit is extended, and means for restoring said indicator to normal when said link circuit is extended to a telephone. line of a certain character.

In witness whereof, we hereunto subscribe our names this 28rd day of August, A. 1)., 1920.

LEO KELLER.

CHARLES L. GOODRUM, 

